This invention relates to supplying or delivering flowable materials usually liquids but feasibly anything, such as pastes or gels or even dry comminuted forms, capable of progressive pressurised delivery, as by piston-and-cylinder or peristaltic pump action, including (though not limited to) accurately controlled delivery in or at low quantities or rates over extended periods of time.
This invention arises specifically in relation to parenteral administration of drugs etc to patients, where requirements can be for substantially continuing dosing with drugs etc, often at very low-dosage rates or levels and over long periods of time, or for such frequent dosing that consistent timely administration dose-by-dose can be problematic even by health-care professionals for hospitalised patients. Resort is generally made to so-called syringe on infusion pumps that are normally driven by precision-geared rotary electric motors closely controlled and monitored by complex microprocessor-based electronic systems. Alternative drive systems include gas pressure as from inflated balloons, typically involving drugs etc delivery through a very small metering hole requiring micro-filtering of drugs etc. Such known syringe or infusion pumps tend to be bulky and expensive, often costing hundreds even thousands of pounds sterling. Patients concerned are necessarily virtually incapacitated during such drugs etc administration, though often, in themselves, not otherwise much debilitated.
It is a specific object of one aspect of this invention to provide, for substantially continuous and/or long tern use by patients, parenteral drugs etc delivery systems with inherent reliability but more convenient to use and/or less expensive, further preferably including capability for embodiment in forms so portable as to be wearable with reasonable safety.
However, in pursuing practical development, many further embodiments with other potentially highly advantageous applications and uses have come into consideration.
According to this invention, there is provided a materials delivery device having administration means that is progressively operable in a step-wise manner by intermittently incremental drive transmission means. For drugs etc administration, increment sizes and intervals between them can correspond to patients"" dosage requirements.
Preferred incremental drive transmission means is of ratchet-type. Intermittently driven toothed pawl means can serve for movement of toothed actuator means in a one-way and non-returnable incremental manner, usually one tooth pitch each time. The toothed pawl means may be reciprocable, conveniently driven one way and released automatically by biasing, say suitable spring means. The pawl means may move the actuator in its drive stroke, or on its return stroke, and will usually deflect for its stroke not driving the actuator means. Preferred toothed pawl means is linearly driven, conveniently repeatedly by simple linear solenoid means, though rotary solenoids are known and could be used.
In piston-and-cylinder type delivery devices, spurting may be mitigated by energy storage-and-release provision between the piston-rod and the piston it drives, or between two parts of the piston-rod, say a spring compressed by a solenoid-driven drive stroke of the pawl means and expanding to drive the piston; and can further have an electric switch operative after energy release corresponding to full stroke piston movement. Another useful provision is ratchet latching means preventing any backward movement beyond increments of the actuator means, say a one-way deflecting latch arm or tooth, which can advantageously have associated even incorporated signalling means, for example including a piezoelectric device.
Such signalling means and switch provisions facilitate highly advantageous control and monitoring of each solenoid-driven delivery increment in terms of adequacy of movement of the actuator means represented by signalling means output for one full tooth deflection and return of the latch means and one full piston delivery stroke represented by switch operation neither too quickly nor too slowly; say as consecutive possible disables in an allowed delay period for an alarm state primed by each solenoid drive pulse. Desired setting up for regular pulses causing solenoid-driven incremental administrations is readily subject to augmenting by on-demand action to generate an additional solenoid drive pulse.
Suitable toothed actuator means can be a linear track of teeth provided on or directly associated with a drive rod of an administration piston, or be an intermediary toothed wheel, whether of simple or complex type, including gearing down via a lesser ring of teeth in rack-and-pinion relation with toothed piston drive rod means, or operative via threading in lead-screw relation with threaded piston drive-rod means. Up to many hundreds, indeed thousands, of increments can be provided in these ways in highly compact even user-wearable battery-powered devices.
Instead of operating delivery pistons of basically syringe-type delivery devices, whether or not for drugs etc administration, solenoid-operated toothed pawl means and ratchet-type drive transmission hereof may be applied to other delivery devices, including advantageously of a peristaltic nature, say where a toothed actuator wheel further carries or is in driving association with tube squeezing and supply metering roller means, such as an annular array of rollers also on or fixed to rotate as a whole array with the ratchet wheel and acting on the tube against support means, preferably biassed and tolerant of different tube sizes.
Advantageous parenteral drugs etc delivery devices of this invention using electric solenoid drive and ratchet-type incremental drive transmission are dramatically less expensive to produce for sale at much lower prices than presently available precision-geared rotary electric motor driven and microprocessor-controlled syringe or infusion pumps. Notably, preferred control and monitoring provisions can be much simpler, say switch and gate based relative to a clock source, and a counter, but still provide full monitoring and reliability of operation. Battery-powered compact units can be fully portable, even safely worn by users including in bed while sleeping, as will be described in detail.
A pre-loaded drugs etc cartridge may be used with its customary sealing and unloading piston operated by said piston-rod of piston-and-cylinder type delivery devices hereof. Alternatively, drugs etc contents may be drawn from a container, often also of pre-loaded type, perhaps particularly for peristaltic type delivery devices hereof. Other applications, for example in the food industry for metering various additives, may use either type of delivery device, including much larger than usual for drugs etc.
In one piston-and-cylinder embodiment of this invention, a holder for a pre-loaded cartridge complete with seal and dispensing piston may be cylindrical with the cartridge at a relatively forward position and the piston-rod relatively rearward in the holder alongside ratchet-drive transmission provisions. The piston-rod will be incrementally movable forwards in driving the piston along the cartridge. The pawl means will be reciprocable by intermittent operation of a rearward drive solenoid and bias-driven return. A hollow delivery needle from the cartridge can be selectively exposable at least for its pointed end. One suitable such needle provision has a medial bend or joint, such as at an angle to a deflectable tube, together with means for forcing its end out of the holder or extension thereof. Such forcing means may be operated by another solenoid at the forward end of the holder. This other solenoid action could be with a time delay for a prescribed number of first solenoid operations to fill the delivery needle before it is extended into the user. The whole may be mounted in a flattish carrier, including control and monitoring electronics and an electric battery, say mounted parallel with the holder in the carrier adapted to be worn by the user.
Other piston-and-cylinder embodiments of this invention can have other configurations and relationships, between their piston-rods, usually along with aligned drugs etc cartridges, and their ratchet-drive pawl means. Thus, a ratchet-wheel with larger and smaller rings of teeth, one (usually the smaller) in rack-and-pinion relation with piston-rod teeth, allows any angled/offset relationship, of which a parallel but offset relationship will be described in detail. For a ratchet-wheel in lead-screw relation with piston-rod threading, a transverse relationship is convenient between the directions of movement of the piston-rod and the reciprocal pawl mens.
Embodiments with peristaltic action, conveniently also using a ring-toothed ratchet-wheel but now with a concentric ring of tube-squeezing rollers can simply draw drugs etc (or any other suitably flowable material) from any container in any relative disposition, whether as a cartridge in the same enclosure or clipped thereto, or separate therefrom, or of some other nature, such as an intravenous (IV) drip-feed bag or whatever. Suitable squeezable peristaltic feed tubes can pass between the ratchet-wheel rollers and pressure-plate means as the support means, preferably biassed towards the rollers, say with a recess to increase length of its engagement by squeezing rollers.
Alternatively, the ring of rollers may be within a U-shaped constraining wall with the peristaltic tube passing between the rollers and the wall, say from connections at and through an end wall. Generally, in addition to varying ratchet drive or tooth/radius parameters, peristaltic-type devices hereof allow variation of capacity and performance simply by a range of different tube diameters. Moreover, a peristaltic embodiment having two similar tubes is capable of highly accurate fluid transfer, particularly operated by the same tube-squeezing rollers, as in taking out and returning body fluids (such as blood) in relation to out-of-body treatments.